Photodynamic therapy (PDT), photodynamic diagnosis (PD), or photochemotherapy is generally used to treat and/or diagnose several types of ailments in or near the skin or other tissues, such as those in a body cavity. For example, photodynamic therapy or photodynamic diagnosis may be used for treatment or diagnosis of actinic keratosis of the upper extremities (e.g., the dorsal surface of the hand or forearms), scalp or facial areas of a patient. In addition, such techniques may be used for treatment and diagnosis of other indications (e.g., acne, warts, psoriasis, photo-damaged skin, cancer) and other areas of the patient (e.g., the legs or portions of the arms other than the forearms).
During one form of photodynamic therapy, a patient is first administered a photoactivatable agent or a precursor of a photoactivatable agent that accumulates in the tissue to be treated. The area in which the photoactivatable agent is administered is then exposed to visible light, which causes chemical and/or biological changes in the agent. These changes allow the agent to then selectively locate, destroy, or alter the target tissue while, at the same time, causing at most only mild and reversible damage to other tissues in the treatment area. One example of a precursor of a photoactivatable agent is 5-aminolevulinic acid (“ALA”), which is commonly used in photodynamic therapy of actinic keratosis. As they are used here, the terms ALA or 5-aminolevulinic acid refer to ALA itself, precursors thereof, esters thereof and pharmaceutically acceptable salts of the same. Photosensitization following application of a topical composition (e.g., a topical solution or emulsion) containing ALA occurs through the metabolic conversion of aminolevulinic acid to protoporphyrin IX (PpIX), as discussed in more detail below. PpIX is a photosensitizer which accumulates in the skin.
For photodynamic therapy to be effective, it is desirable to have a power output that can be controlled for intensity and duration, among other factors. Illuminators are typically used to provide the proper uniformity of light for treatment purposes. These devices generally include a light source (e.g., a fluorescent tube or LED), coupling elements that direct, filter or otherwise conduct emitted light so that it arrives at its intended target in a usable form, and a control system that starts and stops the production of light when necessary.
Photodynamic therapy may be carried out using certain compositions, such as ALA, in connection with illuminators as described above. Such compositions and/or devices are disclosed, for example, in (1) U.S. Pat. No. 5,954,703 to Golub, entitled “Method and apparatus for applying 5-aminolevulinic acid,” issued on Sep. 21, 1999, (2) U.S. Pat. No. 6,223,071 to Lundahl et al., entitled “Illuminator for photodynamic therapy and diagnosis which produces substantially uniform intensity visible light,” issued on Apr. 24, 2001, (3) U.S. patent application Ser. No. 15/371,363 to Boyajian et al., entitled “Method And Apparatus For Applying A Topical Solution,” published on Jun. 8, 2017 as U.S. Pub. No. 2017/0157379, (4) International Application No. PCT/US2016/056572 to Boyajian et al., entitled “Adjustable Illuminator For Photodynamic Therapy And Diagnosis,” published on Apr. 20, 2017 as WO 2017/066270, (5) U.S. patent application Ser. No. 15/292,731 to Boyajian et al., entitled “Adjustable Illuminator For Photodynamic Therapy And Diagnosis,” published on Apr. 20, 2017 as U.S. Pub. No. 2017/0106205, and (6) U.S. patent application Ser. No. 15/487,991 to Boyajian et al., entitled “Adjustable Illuminators And Methods For Photodynamic Therapy And Diagnosis,” published on Aug. 3, 2017 as U.S. Pub. No. 2017/0216616. The entire contents of the foregoing patents and/or patent applications (1)-(6) are incorporated herein by reference for background information and the compositions, devices, processes and techniques relating to photodynamic therapy and diagnosis disclosed therein.